Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2014	$ 500,689		$ 21	$ 267,206	$ 285,937	$ (49,994)	$ (2,481)
Balance (in shares) at Dec. 31, 2014			19,430			1,606
Net income	39,369				39,369
Other comprehensive income (loss)	(5,010)	[1]					(5,010)
Equity compensation	10,850			10,392		$ 458
Exercise of stock options	932			932
Exercise of stock options (in shares)			44
Issuance of shares pursuant to vesting of restricted stock units			234
Net payments for stock issuances and buybacks	(24,861)			276		$ (25,137)
Net payments for stock issuances and buybacks (in shares)			(676)			676
Tax impact of stock option exercises and award vesting	1,307			1,307
Balance at Dec. 31, 2015	523,276		$ 21	280,113	325,306	$ (74,673)	(7,491)
Balance (in shares) at Dec. 31, 2015			19,032			2,282
Net income	46,584				46,584
Other comprehensive income (loss)	(2,149)	[1]					(2,149)
Equity compensation	9,082			8,734		$ 348
Exercise of stock options	3,034		$ 1	3,033
Exercise of stock options (in shares)			128
Issuance of shares pursuant to vesting of restricted stock units			221
Net payments for stock issuances and buybacks	(13,823)			547		$ (14,370)
Net payments for stock issuances and buybacks (in shares)			(360)			360
Balance at Dec. 31, 2016	566,004		$ 22	292,427	371,890	$ (88,695)	(9,640)
Balance (in shares) at Dec. 31, 2016			19,021			2,642
Net income	62,876				62,876
Other comprehensive income (loss)	4,601	[1]					4,601
Equity compensation	10,291			9,985		$ 306
Exercise of stock options	4,722			4,722
Exercise of stock options (in shares)			176
Issuance of shares pursuant to vesting of restricted stock units			180
Net payments for stock issuances and buybacks	(32,464)			687		$ (33,151)
Net payments for stock issuances and buybacks (in shares)			(715)			715
Balance at Dec. 31, 2017	$ 616,030		$ 22	$ 307,821	$ 434,766	$ (121,540)	$ (5,039)
Balance (in shares) at Dec. 31, 2017			18,662			3,357

[1] Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.